Fix test regarding the new url return of asset upload
Fix test regarding the new url return of asset upload

refs #472

rickmak/skygear-server,SkygearIO/skygear-server,SkygearIO/skygear-server,SkygearIO/skygear-server,rickmak/skygear-server,SkygearIO/skygear-server,rickmak/skygear-server